Novel Liquid Multi-functional Branched Polysiloxane And Its Modified Bismaleimide/diallylbisphenol A Resins With Simultaneously Improved Integrated Performances

Bismaleimide(BMI) is a typical representative of heat-resisting thermosetting resins(TS), which has been of great value in aerospace, electronic information and electrical insulation and other fields. Toughening has been one hot and challenge topic on studying TS resins. With the increasing requirements of cutting-edge fields on multi-functional resins, TS resins should not only have high thermal resistance and high toughness, but also should simultaneously possess outstanding flame retardancy. However, it is a tricky problem that a modifier possesses multi-functions. To solve these problems existed in TS,we carried our research reported in this thesis, which includes following three aspects.First, a novel liquid multi-maleimide branched polysiloxane(PMI-HSi) was synthesized through the reaction between maleic anhydride(MA) and γ-aminopropyl triethoxysilane(KH-550), and thoroughly characterized. Results show that PMI-HSi is a liquid, and contains a great deal of active groups that can react with BMI, leading to good processing characteristics, providing a good foundation of obtaining improved integrated performances for the modified resinsSecond, a new modified bismaleimide resin was developed by copolymerizing 4,4’-bismaleimidodiphenyl methane/2, 2’-diallyl bisphenol A(BD) with PMI-HSi, and the influence of PMI-HSi on the integrated performances of BD resin was investigated.Research shows that compared with BD resin, PMI-HSi/BD resins have higher crosslinking densities, greatly improved mechanical properties(impact and flexural strengths) while maintaining high glass transition temperature, initial thermal decomposition temperature and flexural modulus, good dielectric properties and moisture resistance. In addition, the high char yield at 800 o C from microscale combustion calorimeter tests indicates that the modified resins also have flame retarding potential.Third, the flame retardancy and mechanism of PMII-HSi/BD resins were intensivelydiscussed. The modified resins show excellent flame retardancy(limited oxygen index,heat release, smoke production), because these modified resins have more stable crosslinking structure, and the Si-O-Si segments in PMI-HSi take part in the char forming.These factors change the combustion behavior and flame retarding mechanism of BD resin.